Apparatus for diluting acids and alkalies



1955 w. M. GAYLORD, JR. ETAL 3,201,205

APPARATUS FOR DILUTING ACIDS AND ALKALIES Filed March 15, 1961 2 Sheets-Sheet 1 146/0 j M4 TE? FIG.

"ll-III. lug" W.

\ INVENTORS W/Ll/A/V IV. 64710:?0 Jr.

BY C

4 ATTORNEY JOS'P/V E AWorrE Aug. 17, 1965 w. M. GAYLORD, JR, ETAL 3,201,205

APPARATUS FOR DILUTING' ACIDS AND ALKALIES Filed March 15, 1961 2 Sheets-Sheet 2 WATL'E INV EN TORS BY 9 M, %/1 rrom/fr United States Patent Oflice 3,2dl2d5 Patented Aug. 17, 1965 3,201,295 APPARATUS Fflll DILUTTNG ACIDS I AND ALKALIES William M. Gaylord, in, New Canaan, Conan, and Joseph F. Knott Ill, Westchester, llll., assignors to Union Carhide Corporation, a corporation of New York Filed Mar. 15, 1961, Ser. No. 95,363 llil Claims. (til. 23-2553) This invention relates to the dilution of a highly concentrated solution of an acid or alkali of the type which reacts exothermically when admixed with a weak aqueous diluting solution, and has for its principal object to provide an improved method and apparatus for diluting and cooling a highly concentrated acid or alkali of this type.

More specifically, another object is to provide such a method and apparatus by which a highly concentrated acid or alkali is thoroughly diluted before the diluted product is cooled.

Another object is to provide such a method and apparatus by which a highly concentrated acid or alkali may be diluted at temperatures above those at which vapor is released during dilution.

Still another object is to provide such a method and apparatus by which a highly concentrated acid or alkali is capable of being diluted in a single pass and over a wide range of flow rates, and by which a wide range of concentrations for the diluted product is capable of being produced.

The invention by means of which these objects are achieved will now be described with particular reference to the accompanying drawings in which:

FIG. 1 is a vertical elevation partially in section of apparatus embodying the invention;

FIG. 2 is an enlarged view of the top portion of apparatus shown in FIG. 1;

FIG. 3 is a plan view taken along the line 3-3 of FIG. 2;

FIG. 4 is a sectional view taken along the line 4-4 of FIG. 2;

FIG. 5 is a similar view taken along the line 5-5 of FIG. 2; and

FIG. 6 is a similar view taken along the line 6-6 of FIG. 2.

According to the invention a highly concentrated solution of an acid or alkali of the type which reacts exothermically with a weak aqueous diluting solution is diluted in apparatus comprising the combination of a diluting header and a falling film type vertical heat exchanger. The diluting header has a cover provided with inlet nozzles for introducing the highly concentrated acid or alkali and diluting solutions and comprises an upper diluting chamber within which a mixer cap is mounted below the cover, which mixer cap provides a mixing zone into which the solutions are passed. The inlet nozzles are angularly bored and preferably disposed at an angle slightly oblique to the diameter of the cover by which the highly concentrated acid or alkali and diluting solutions pass as tangentially impinging fluid streams into the mixer cap. The tangential impingement of the fluid streams causes the solutions to swirl and to be admixed thereby in the mixer cap. The mixer cap has several rows of distributing ports in its side walls which substantially uniformly distribute the admixed solutions throughout the upper chamber in the header. The admixed solutions then pass down through the upper chamber and the direction of flow therethrough is changed by baffle means provided in the header, whereby thorough admixing and dilution is achieved. The diluted product then passes to a lower distribution chamber in the header and is substantially evenly distributed in a falling film through a plurality of upstanding weir tubes to the heat exchanger.

For the sake of conciseness, the invention will now be described in greater detail with particular reference to the dilution of a highly concentrated acid such as, for example, sulfuric acid with water, although it will be understood that the principles to be disclosed are applicable as well to the dilution of a highly concentrated alkali, for example, sodium hydroxide.

Referring now to the drawings, apparatus embodying the invention comprises a diluting header H and a falling film type vertical heat exchanger E as shown in FIG. 1. The header H and heat exchanger E are composed of a corrosion resistant material, for example, impervious graphite unless otherwise indicated. The header H has a cover ltl provided with a pair of inlet nozzles l2, 14 for introducing the acid to be diluted and water respectively.

The heat exchanger E comprises a steel shell 16 vertically mounted on a metal frame 18. The shell 16 contains a plurality of heat transfer tubes 26 which are secured within a tube sheet 22. The tubes 2% pass through metal bafile plates 24 supported by metal tie rods 26. lnlet and outlet means 28, 30 respectively are provided for circulating coolant water through the shell 15.

The cover it? and header H are bolted to the tube sheet 22 between a metal cover flange 32 and a top flange 34 on the shell 16. At the bottom of the shell 16, a bottom cover 36 having a discharge nozzle 38 for recovering the diluted acid product is bolted between a metal cover flange 4t) and a bottom cover flange 42 on the shell 16.

The header H comprises generally cylindrical side walls 44 and has an integrally formed false bottom wall 46 which is spaced a distance above the tube sheet 22 and which thereby separates the header H into an upper diluting chamber 48 and a lower distribution chamber 5t).

Within the diluting chamber 48 an annular shaped horizontal baffle 52 is integrally formed with the side walls 44 and a cylindrical mixer cap 54 is threaded within the bottom of the cover lit. The bottom portion of the side walls 44 is of a generally thicker dimension and has formed therein an annular labyrinth passage 56, the innermost wall of which is provided with a number of uniformly spaced outlets as indicated at 531 which open into the distribution chamber 50, there being eighteen such outlets of a substantially V shaped in the construction shown. The bottom wall 46 is bored and threaded to receive a standpipe 6t and is tapered downwardly towards a plurality of circumferentially arranged vertical conduits 62 which lead into the labyrinth passage 56. A plurality of weir tubes 64 are threaded into the tube sheet 22 within the distribution chamber which communicate directly with the tubes 20 in the heat exchanger E.

Acid and water enter through the inlet nozzles 12, 14 respectively in the cover it The inlet nozzles 12, 14 are angularly bored in the cover it) and the acid and water thus pass therefrom as a pair of impinging fluid streams within the upper centermost portion of the mixer cap 54 as indicated in enlarged detail in FIG. 2. As shown in FIG. 3, the inlet nozzles l2, 14 are preferably also oppositely disposed at an angle slightly oblique to the diameter of the cover 10 suflicient to effect tangential impingement of fluid streams of acid and water. It will thus be observed by this construction that acid and water are caused to swirl in a somewhat violent spray and to be thereby admixed. The inlet nozzles 12, 14 preferably should be disposed at such an angle with respect to the diameter of the cover 10 that one-fourth of the cross-sectional areas of the fluid streams intersect. The admixed solutions then collect in the bottom of the mixer cap 54.

The side walls of the cylindrical mixer cap 54 are pro- The diluted product is then cooled in the heat exchanger and recovered therefrom.

vided with several rows of a plurality of ports as indicated at 63, 68a and 68b in FIG. 2. Referring to FIGS. 4 and 6, the top and bottom row of ports indicated at 6% and 68b respectively are disposed at an angle oppositely oblique to the radius of the mixer cap 54, an angle of about 30 degrees being preferred, for example. The middle row of ports indicated at 68a are radially disposed as shown in FIG. 5. Thus, it will be seen that acid and water pass from the mixer cap 54 where they are admixed in several different directions through the plurality of ports, a major part of the flow of which is preferably made to impinge against the interior side walls 44, and are thereby uniformly distributed throughout the uppermost portion of the diluting chamber 48. The bottom wall of the mixer cap 54 is also preferably provided with ports as indicated at '70, 76a, there being four circumferentially arranged ports in the construction illustrated, for directing a small quantity of the admixed solutions downwardly to the bottom of the diluting chamber 4-8.

The admixed acid and water then pass down along the side walls 44 through the diluting chamber 43, the flow of which is then directed radially inward by the annular baffle 52. The baffie 52 breaks the fall of acid and water which then pass to the bottom of the diluting chamber 48. It will thus be appreciated that acid and water which are introduced into the header H are at least partially admixed in the mixer cap 54- and that by reason of the substantially uniform distribution of the solutions thereby admixed throughout the diluting chamber 48 and the turbulent action imparted to the fiow of the solutions therethrough, additional admixing and thorough dilution of the acid is achieved.

The diluted acid is then collected in the lower distribution chamber 50 from whence it is passed to the heat exchanger E for cooling. The diluted acid passes through the plurality of conduits 62 which lead into the labyrinth passage 56 and is evenly distributed through the uniformly spaced V openings 58 in the inner wall of the passage 56 to the chamber 50 where it collects in a pool. The level of the pool is maintained by the plurality of weir tubes 64 whose upper rims are provided with overflow notches 72. These notches 72 are tangenially disposed in the weir tubes 64 and serve to uniformly distribute the diluted acid in a falling film type flow down through the tubes in the shell 16. The diluted acid is cooled by the countercurrent flow of coolant water circulated through the shell 16. The cooled diluted acid product is then collected within the bottom cover 36 and is recovered through the discharge nozzle 33. A wier tube construction of the type described which is particularly Well suited for use with the invention is disclosed in US. Patent No. 2,859,021 issued to S.H.S. Raub et al. on November 4, 1958.

During dilution of the acid, it may be encountered that vapor is formed in the diluting chamber 48, the proper venting of which is essential to preventing the build-up of pressure and the creation of high localized temperatures in the header H. With the construction described, it will be observed that any vapor which may be released is vented down through the standpipe 64 into the distribution chamber 59. The vapor is then passed down into the tubes 24) together with the diluted acid wherein the vapor is condensed and absorbed into the acid. The standpipe 60 also serves to provide a means for displacing air'during start-up and for equalizing the pressure between the diluting and distribution chambers 38, Stl.

It will thus be apparent that the invention provides for the dilution of a highly concentrated acid or alkali of the type which reacts exothermically with a weak aqueous diluting solution in which the acid or alkali is thoroughly diluted before cooling of the diluted product. This is highly advantageous for heat of dilution is fully released during the diluting stage of the process and practically no heat is therefore evolved when the diluted product is cooled.

Another advantages which is derived from the invention is that a highly concentrated acid or alkali may be diluted in a single pass over a wide range of concentrations and at varying fiow rates of acid or alkali and diluting water introduced. This is made possible by the high dilution rate capacity of the header and the provision of a falling film type heat exchanger. By way of illustration, apparatus embodying the invention is capable of producing diluted acids ranging from the most concentrated made commercially, 99% acid, to the most dilute commonly utilized in industry, 15% acid.

Another important advantage of the invention is derived from the mixer cap arrangement which serves to break the continuity of fiow of acid or alkali and diluting water through the header. Thus, there is no chance for back-up of acid or alkali after shutdown into the inlet water line system. Still another advantage is that apparatus embodying the invention is operable solely by gravitational flow of acid or alkali and diluting solution down through the header and heat exchanger, the only pressure needed for operation is that necessary to bring the entering solutions to the top cover of the header.

As an example of the invention, apparatus was constructed for the dilution of a highly concentrated sulfuric acid substantially as shown in FIG. 1. A header was fabricated of impervious graphite approximately two feet in height and having a diameter of 22% inch O.D., which was bolted to an impervious graphite falling film vertical heat exchanger. The cover for the header was of approximately the same diameter and had a pair of inlet nozzles two inches in diameter bored therein at an angle of 21% degrees with respect to its vertical axis and at an angle of 9 degrees with respect to the diameter of the cover. A mixer cap having a diameter of 15 inches O.D. was threaded into the bottom of the cover and had provided therein three rows of distribution ports approximately inch in diameter, the top and bottom rows of which consisted of 33 ports drilled in oppositely oblique angles of 30 degrees. The middle row of ports consisted of 10 holes /2 inch in diameter. The concentration of the acid was about 99.2% acid and was diluted through a range of concentration of from about 93.6% to 67.1% acid. The product acid rate varied from 635 lbs./(hr.)-(tube) to 95.8 lbs./ (l1r.)-(tube), and the temperature of the acid product ranged from F. to 117 F.

It will be understood that various modifications and adaptations of the principles of the invention will be apparent to those skilled in the art. Instead of impervious graphite, for example, other corrosion resistant materials such as steel may be used in the construction described. Nickel is a suitable material when diluting a highly concentrated alkali. Other similar modifications may, of course, be made without departing from the spirit and scope of the invention.

What is claimed is:

1. In combination, a diluting header and a heat exchanger for diluting and cooling a highly concentrated solution of an acid or alkali of the type which reacts exothermically with a weak aqueous diluting solution; said header having a cover provided with angularly disposed inlet nozzle means for introducing said solutions as impinging fiuid streams into said header and comprising an upper diluting chamber, a lower distribution chamber and passage means between said chambers; a mixer cap in said upper chamber mounted within the bottom of said cover below said inlet nozzle means, said mixer cap having a plurality of distribution ports therein; bafile means in said upper chamber; vapor venting means between said chambers for venting said upper chamber to said lower chamber and for equalizing the pressure between same; and means in said distribution chamber for distributing the diluted product from said header to said heat exchanger for cooling.

2. In combination, a diluting header and a falling film type vertical heat exchanger for diluting and cooling a highly concentrated solution of an acid or alkali of the type which reacts exothermically with a weak aqueous diluting solution; said heat exchanger having a shell, a tube sheet, a plurality of heat transfer tubes in said shell secured within said tube sheet and inlet and outlet means for a coolant; said header having a cover provided with angularly disposed inlet nozzles for introducing said solutions as impinging tangentially intersecting fluid streams into said header and comprising side walls and a bottom wall spaced above said tube sheet, said bottom wall dividing said header into an upper diluting chamber and a lower distribution chamber and passage means between said chambers; a mixer cap in said upper chamber mounted within the bottom of said cover, said mixer cap having a plurality of distribution ports therein; baffle means in said upper chamber; vapor venting means in said bottom wall of said header for venting said upper chamber to said lower chamber and for equalizing the pressure between same; and a plurality of upstanding weir tube means in said distribution chamber secured within said tube sheet for distributing the diluted product from said header to said heat transfer tubes for cooling.

3. The combination defined by claim 2 in which said angularly disposed inlet nozzles are arranged in said cover in such relation that one-fourth of the cross-sectional areas of said fluid streams intersect.

4. The combination defined by claim 2 in which said weir tube means are provided with tangentially disposed overflow notches.

5. Apparatus for diluting and cooling a highly concentrated solution of an acid or alkali of the type which reacts exothermically with a weak aqueous diluting solution comprising, in combination, a generally cylindrical diluting header and cover therefor having angularly disposed inlet nozzles therein for introducing said solutions into said header; a vertically supported shell having a top flange and a bottom flange; a tube sheet; a cover flange; said header and cover being bolted to said tube sheet between said cover flange and said top flange; said shell,

containing a plurality of heat transfer tubes secured within said tube sheet and having inlet and outlet means for circulating coolant through said shell; a bottom cover having discharge nozzle means; a bottom cover flange; said bottom cover being bolted between said bottom cover flange and said bottom flange; said header comprising generally cylindrical side walls and a bottom wall spaced above said tube sheet, said bottom wall dividing said header into an upper diluting chamber and a lower distribution chamber, and passage means between said chambers; a generally cylindrical mixer cap in said upper chamber mounted into the bottom of said cover below said inlet nozzles, said mixer cap having several rows of distribution ports in the side wall thereof; baffle means in said upper chamber; vapor venting means in said bottom wall of said header for venting said upper chamber to said lower chamber and for equalizing the pressure between same; and a plurality of upstanding weir tubes having tangentially disposed overflow notches in said distribution chamber, said weir tubes being mounted within said tube sheet and communicating with said heat transfer tubes in said shell.

6. Apparatus as defined by claim 5 in which said inlet nozzles are also disposed at an angle slightly oblique to the diameter of said cover for passing said solutions as tangentially impinging fluid streams into said mixer cap.

7. Apparatus as defined by claim 5 in which each of said 6 several rows of distribution ports in said mixer cap are disposed in different directions in said upper chamber.

8. Apparatus as defined by claim 5 in which said passage means comprises a plurality of conduits in said bottom wall communicating with an annular passage in said side wall having a plurality of uniformly spaced outlets which open into said distribution chamber.

9. Apparatus as defined by claim 5 in which said vapor venting means comprises a standpipe mounted in said bottom wall in said upper chamber.

10. Apparatus for diluting and cooling a highly concentrated solution of an acid or alkali of the type which reacts exothermically with a weak aqueous diluting solution comprising, in combination, a generally cylindrical diluting header and cover therefor, said header comprising said walls and a bottom wall spaced above the bottom of said header and dividing said header into an upper diluting chamber and a lower distribution chamber, the bottom portion of said side walls being of a generally thicker dimension and having formed therein an annular passage, said annular passage having a plurality of uniforrnly spaced outlets which open into said distribution chamber, said bottom wall having a plurality of conduits communicating with said annular passage, said side walls being provided with an annular baffle in said upper chamber, said cover having inlet nozzles angularly bored therein and disposed at an angle slightly oblique to the diameter of said cover for introducing said solutions as impinging fluid streams into said upper chamber; a generally cylindrical mixer cap in said upper chamber mounted into the bottom of said cover below said nozzles, said mixer cap having several rows of distribution ports in the side wall thereof, the ports in each row of which are disposed in different directions in said upper chamber; a venting standpipe in said upper chamber mounted in said bottom wall of said header for venting said upper chamber to said lower chamber and for equalizing the pressure between same; a vertically supported shell having a top flange and a bottom flange; a tube sheet; a cover flange; said header and cover being bolted to said tube sheet between said cover flange and said top flange; a plurality of heat transfer tubes in said shell secured within said tube sheet; a plurality of upstanding weir tubes in said distribution chamber mounted within said tube sheet, said weir tubes having tangentially disposed overflow notches for producing a falling film flow of diluted product down through said weir tubes and into said heat transfer tubes, said shell having inlet and outlet means for circulating coolant countercurrently to the flow of diluted product through said heat transfer tubes; a bottom cover having discharge nozzle means; a bottom cover flange; said bottom cover being bolted between said bottom cover flange and said bottom flange on said shell.

References Cited by the Examiner UNITED STATES PATENTS 758,450 4/04 Joseph 23-1 1,562,827 11/25 Fothergill 261-149 1,662,932 3/28 Miscampbell 23--287 1,907,455 5/33 Stenzel 231 2,872,297 2/59 Dugan 23--285 2,950,180 8/60 Kunzer et a1 23283 MORRIS O. WOLK, Primary Examiner.

MAURICE A. BRINDISI, JAMES H. TAYMAN, 1a.,

Examiners. 

1. IN COMBINATION, A DILUTING HEADER AND A HEAT EXCHANGER FOR DILUTING AND COOLING A HIGHLY CONCENTRATED SOLUTION OF AN ACID OR ALKALI OF THE TYPE WHICH REACTS EXOTHERMICALLY WITH A WEAK AQUEOUS DILUTING SOLUTION; SAID HEADER HAVING A COVER PROVIDED WITH ANGULARLY DISPOSED INLET NOZZLE MEANS FOR INTRODUCING SAID SOLUTION AS IMPINGING FLUID STREAMS INTO SAID HEADER AND COMPRISING AN UPPER DILUTING CHAMBER, A LOWER DISTRIBUTION CHAMBER AND PASSAGE MEANS BETWEEN SAID CHAMBERS; A MIXER CAP IN SAID UPPER CHAMBER MOUNTED WITHIN THE BOTTOM OF SAID COVER BELOW SAID INLET NOZZLE MEANS, SAID MIXER CAP HAVING A PLURALITY OF DISTRIBUTION PORTS THEREIN; BAFFLE MEANS IN SAID UPPER CHAMBER; VAPOR VENTING MEANS BETWEEN SAID CHAMBERS FOR VENTING SAID UPPER CHAMBER TO SAID LOWER CHAMBER AND FOR EQUALIZING THE PRESSURE BETWEEN SAME; 